Predicting Operational Problems in a Hard-Disk Drive (HDD)

ABSTRACT

A method and apparatus for determining the likelihood that a hard-disk drive (HDD) will experience an imminent error in operation is provided. The HDD comprises a differential pressure sensor capable of measuring the difference in the pressure between the interior and the exterior of the enclosure. The differential pressure sensor may reside in a breather filter covering an air passage within the enclosure. The HDD also comprises a risk assessment component capable of (a) determining an expression of how likely it is that the HDD will experience an imminent error in operation based, at least in part, upon the difference in pressure measured by the pressure sensor, and (b) communicating the expression to a user of the HDD. The HDD may optionally comprise one or more of an atmospheric pressure sensor, a particle counter, and a chemical vapor sensor which may be used by the risk assessment component.

RELATED APPLICATION DATA

This application is related to U.S. patent Ser. No. 12/______, Attorneydocket number HGS_(—)1005, entitled Using an Atmospheric Pressure Sensorin a Hard-Disk Drive (HDD), filed by Norbert Feliss, et al. on the sameday as the present application, the contents of which are hereinincorporated by reference as if originally set forth herein.

FIELD OF THE INVENTION

Embodiments of the invention relate to predicting an operational problemin a hard-disk drive (HDD).

BACKGROUND OF THE INVENTION

The operation of certain computer equipment can be negatively affectedby the presence of environmental hazards, such as airborne contaminants.To prevent this harm from occurring, some sensitive equipment may behoused in an enclosure that is designed to keep out airbornecontaminants.

An example of a piece of sensitive equipment housed within a protectiveenclosure is a hard-disk drive (HDD). An HDD is a non-volatile storagedevice, which is housed in a protective enclosure, that stores digitallyencoded data on one or more circular platters having magnetic surfaces.When an HDD is in operation, each platter is rapidly rotated by aspindle system. Data is read from and written to a platter using aread/write head which is positioned over a specific location on aplatter by an actuator.

A read/write head uses a magnetic field to read data from and write datato the surface of a platter. As a magnetic dipole field decreasesrapidly with distance from a magnetic pole, the space between aread/write head and the surface of a platter must be tightly controlled.To provide a uniform distance between a read/write head and the surfaceof a platter, an actuator relies on air generated by a self-acting airbearing to support the read/write heads at the proper distance away fromthe surface of a platter while the platter rotates. A read/write headtherefore is said to “fly” over the surface of a platter. That is, theair pulled along by a spinning platter forces the head away from thesurface of the platter. When a platter stops spinning, a read/write headmust either “land” on the platters or be pulled away.

Very small airborne particles, such as the size of 10 nm to 1000 nm (1micron), may adhere to the air bearing surfaces of either a read/writehead or deposit on the surface of the magnetic platters (disk stack).When the surface of either a read/write head or a platter becomesattached to airborne particles, it is more likely that a read/write headmay not read data properly or may scrape across the surface of aplatter, which could grind away the thin magnetic film of the platterand cause data loss and potentially render the HDD inoperable.

It may be necessary to equalize the pressure between the interior andthe exterior of the HDD in certain situations, such as when thehard-disk drive is turned on or turned off, when the HDD is brought to adifferent elevation (e.g., from sea level to a mountain top), or whenthe temperature of the HDD is much different than the ambienttemperature. To equalize the pressure between the interior and theexterior of the enclosure, the enclosure has a small opening (an “airpassage”) located in the cover of the HDD that allows air to travelbetween the interior and the exterior of the enclosure. The air passageis covered by a filter (referred to as a “breather filter”) that filtersthe air to prevent any airborne particles outside of the enclosure fromentering the interior of the enclosure. When the hard-disk drive is in asteady state (i.e., after it has been turned on or off for a period oftime), there should be no air flow through the air passage covered bythe breather filter, although mass diffusion will still occur.

SUMMARY OF THE INVENTION

Techniques are provided for predicting an operational problem in ahard-disk drive (HDD). Embodiments of the invention predict anoperational problem by detecting a leak in the enclosure of the HDDcaused by an unintentional opening in the enclosure. The presence of theleak within the enclosure of the HDD indicates that harmful airborneparticles or chemical vapors from the exterior of the enclosure havelikely entered the interior of the HDD. Such harmful airborne particlesor chemical vapors may cause the HDD to crash or otherwise experience anoperational problem. Chemical vapors that may leak into the interior ofan HDD are typically hydrocarbon in nature, such as methane gas togasoline as well as siloxane (poly-dimethylsiloxane) gas. A vapordetector employed by an HDD may be selectively tailored and manufacturedto detect a range of hydrocarbon and siloxane (poly-dimethylsiloxane)gases. Embodiments of the invention may inform a user of the HDD of thepresence of the leak so that the user may take appropriate action, suchas backing up data stored on the HDD or servicing the HDD.

In an embodiment, the presence of a leak within the enclosure of the HDDmay be detected by measuring the drop in pressure across the breatherfilter of the HDD. A pressure sensor (referred to herein as a“differential pressure sensor”) capable of measuring the drop inpressure across the breather filter may be positioned within the airpassage covered by the breather filter, as shown in FIG. 6. The flow ofair through the breather filter can be detected with back-to-backmatched thermistors which operate in a self heating mode. Back-to-backmatched thermistors may be implemented using MEMS technology, whichincludes pressure sensors in surface mount packages, fully calibrated,and amplified or having digital output versions. The back-to-backthermistors may detect the flow of air through the breather filter,direction of the flow of air through the breather filter, and thedifference in pressure across the breather filter. If there is no leakwithin the enclosure of the HDD, then there will be no drop in pressureacross the breather filter. However, if there is a leak within theenclosure of the HDD, then there will be a drop in pressure across thebreather filter.

Certain embodiments of the invention may also employ a particle counterwithin the interior of the enclosure to count the number of airborneparticles present within the enclosure. For example, the particlecounter may be used to count the number of airborne particles within theenclosure of the HDD since being manufactured. In this way, the particlecounter can identify whether the number of airborne particles hasincreased since a prior point in time, such as the time of manufactureof the HDD. The differential pressure sensor and the particle countermay be used in combination by embodiments of the invention to assess therisk posed by a leak.

Other embodiments of the invention may employ a chemical vapor sensorwithin the interior of the enclosure to measure the vapor concentrationpresent within the enclosure. The chemical vapor sensor may be used tomeasure the total buildup of chemical vapors within the interior of theHDD since the time of manufacture of the HDD. The differential pressuresensor, particle counter, and chemical vapor sensor may be used in anycombination by embodiments of the invention to assess the risk posed bya leak.

Further embodiments of the invention may employ an atmospheric pressuresensor, which is a sensor which can determine the altitude at which theHDD is presently located. For example, the atmospheric pressure sensormay determine whether the HDD is presently located at sea level or at ahigh elevation. When the HDD is at a relatively high elevation, the riskposed by a leak is greater because the read/write head flies closer tothe surface of the disk than when the HDD is at sea level. Thedifferential pressure sensor, particle counter, chemical vapor sensor,and atmospheric pressure sensor may be used in any combination byembodiments of the invention to assess the risk posed by the leak.

In an embodiment of the invention, when an HDD is turned on, a riskassessment component within the HDD checks data recorded by one or moreof the differential pressure sensor, the particle counter, the chemicalvapor sensor, and the atmospheric pressure sensor to ascertain whetherthere is a leak in the enclosure of the HDD and to assess the risk posedby any such leak. Thereafter, the risk assessment component maycommunicate the assessment of the risk to a user of the HDD.

Embodiments discussed in the Summary of the Invention section are notmeant to suggest, describe, or teach all the embodiments discussedherein. Thus, embodiments of the invention may contain additional ordifferent features than those discussed in this section.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention are illustrated by way of example,and not by way of limitation, in the figures of the accompanyingdrawings and in which like reference numerals refer to similar elementsand in which:

FIG. 1 is an illustration of a plan view of an HDD according to anembodiment of the invention;

FIG. 2 is an illustration of a plan view of a head-arm-assembly (HAA)according to an embodiment of the invention;

FIG. 3A is a flowchart depicting the functional steps involved inpredicting operational problems in an HDD according to an embodiment ofthe invention;

FIG. 3B is a flowchart depicting additional factors to consider whendetermining the expression of risk according to an embodiment of theinvention;

FIG. 4 is an illustration of a cover of an HDD that comprises a breatherfilter according to an embodiment of the invention;

FIG. 5 is an illustration of a base casting of an HDD that comprises abreather filter according to an embodiment of the invention;

FIG. 6 is an illustration of a pressure sensor located within the airflow path of a breather filter according to an embodiment of theinvention;

FIG. 7 is an illustration of the flow of air through a breather filteraccording to an embodiment of the invention;

FIG. 8 is a cross-sectional view of a cover comprising a breather filterwith a diffusion channel according to an embodiment of the invention;and

FIG. 9 is a flowchart depicting the functional steps of correcting thedistance between the heads of an HDD and the disk in response to achange in altitude of the HDD according to an embodiment of theinvention.

DETAILED DESCRIPTION OF THE INVENTION

Approaches for predicting an operational problem in a hard-disk drive(HDD) are described. In the following description, for the purposes ofexplanation, numerous specific details are set forth in order to providea thorough understanding of the embodiments of the invention presentedherein. It will be apparent, however, that the embodiments of theinvention presented herein may be practiced without these specificdetails. In other instances, well-known structures and devices are shownin block diagram form in order to avoid unnecessarily obscuring theembodiments of the invention presented herein.

How Leaks can Occur within an HDD

A hard-disk drive (HDD) may experience a leak by the introduction of anunintended hole or opening in the enclosure of the HDD. An unintendedhole or opening may occur in the enclosure of the HDD in the course ofmanufacturing or by the HDD experiencing a bump. A sudden force assertedagainst the HDD may disrupt an elastomeric filter or seal around ascrew, which may introduce a leak.

Leaks can occur in a variety of locations within the enclosure of theHDD. For example, an unintended hole or opening may be present where thecover attaches to the base, where the motor is attached to the basecasting, where the seal attaches to the base casting, around screws orscrew holes, near the seal between the cover servo-write access holethat is used for the push/pull level of a servo writer, near the sealbetween the particle count hole and the cover, and any small crack orhole in the HDDs base casting or cover caused during manufacturing.These locations are merely illustrative of where an unintended hole oropening may occur, and are not meant to exhaustively identify alllocations where a leak in an HDD may occur.

A potential leak at the mating surface of the cover may be caused bydamage to the cover gasket or by a defect in the casting mating surfaceof the HDD that affects the main cover seal. Seal leaks can be causedafter manufacture or in use by damage to the seal itself. Seals may bemade thick and very robust but to do so affects their ability to besupplied on a roll for automatic manufacturing. In addition, thick sealsmake it hard to manufacture on high speed machines. Another leak paththat is observed in HDDs is caused by the pressure of the electricalcard on the signal bracket, especially if there is a translational androtational mechanical shock.

When an HDD is in operation, the air inside the enclosure of the HDDcirculates due to the spinning of the platters. The circulation of theair within the protective enclosure exerts pressure upon the interiorsurface of the enclosure. This pressure varies based upon location. Thepressure exerted by the circulating air upon the interior surface of theenclosure increases with distance from the center of the spinningplatters. Thus, when the drive is in operation, the pressure exertedupon the interior surface of the enclosure near the center of theenclosure is less than the pressure exerted upon the interior surface ofthe enclosure near the outer edge of the spinning platters. The averagepressure in the HDD is determined by the location of the breatherfilter. An optimum location of the breather filter is at the center ofthe rotating disk pack. However, design or manufacturing constraints mayprohibit this location for the breather filter. The breather filter istypically placed near the periphery of the disk pack, either located inthe cover or inside the base casting. For example, non-limiting,illustrative locations of a breather filter are depicted in FIGS. 4 and5. FIG. 4 is an illustration 400 of a cover of an HDD that comprises abreather filter 410 according to an embodiment of the invention. FIG. 5is an illustration 500 of a base casting of an HDD that comprises abreather filter 510 according to an embodiment of the invention.

The enclosure of an HDD typically includes one intentional hole. Thisintentional hole is used to equalize the pressure between the interiorand the exterior of the enclosure when the HDD is turned on or turnedoff. To prevent airborne particles from entering the interior of theenclosure, the intentional hole is covered by a breather filter, whichfilters the air flowing into the interior of the enclosure of the HDD toprevent any airborne particles from entering into the interior of theenclosure of the HDD. If there are no unintentional holes or openings inthe enclosure of the HDD, then no air flows through the breather filterwhen the HDD is in a steady state. The HDD is in a steady state afterthe HDD has been turned on or off for a certain period of time. The flowof air through the breather filter is also affected by thermal effects,such as the heating and cooling which occurs when the HDD is turned onand off which equalizes the pressure inside the drive to the outsideambient pressure.

However, if there are one or more unintentional holes or openings in theenclosure of the HDD, then there will be a flow of air from a hole oropening in a location at a relatively higher pressure to another hole oropening in a location at a relatively lower pressure. Any unfiltered airthat flows into the interior of the enclosure of the HDD may carryairborne particles or chemical vapors that are harmful to the operationof the HDD. Adding additional airborne particles or chemical vapors intothe interior of the HDD may result in data loss and may potentiallyrender the HDD inoperable. As a result, it would be desirable for a userto know whether or not his or her HDD is experiencing a leak so that theuser could take appropriate action (such as backing up data on the HDDor servicing the HDD) prior to the HDD losing data or becominginoperable.

Having described how leaks may be introduced into an HDD, anillustrative HDD, according to an embodiment of the invention, which iscapable of a detecting a leak and assessing the risk caused thereby,shall now be presented.

Physical Description of Illustrative Embodiments of the Invention

With reference to FIG. 1, in accordance with an embodiment of thepresent invention, a plan view of a HDD 100 is shown. FIG. 1 illustratesthe functional arrangement of components of the HDD including a slider110 b including a magnetic-recording head 110 a. The HDD 100 includes atleast one HGA 110 including the head 110 a, a lead suspension 110 cattached to the head 110 a, and a load beam 110 d attached to the slider110 b, which includes the head 110 a at a distal end of the slider 110b; the slider 110 b is attached at the distal end of the load beam 110 dto a gimbal portion of the load beam 110 d. The HDD 100 also includes atleast one magnetic-recording disk 120 rotatably mounted on a spindle 124and a drive motor (not shown) attached to the spindle 124 for rotatingthe disk 120. The head 110 a includes a write element, a so-calledwriter, and a read element, a so-called reader, for respectively writingand reading information stored on the disk 120 of the HDD 100. The disk120 or a plurality (not shown) of disks may be affixed to the spindle124 with a disk clamp 128. The HDD 100 further includes an arm 132attached to the HGA 110, a carriage 134, a voice-coil motor (VCM) thatincludes an armature 136 including a voice coil 140 attached to thecarriage 134; and a stator 144 including a voice-coil magnet (notshown); the armature 136 of the VCM is attached to the carriage 134 andis configured to move the arm 132 and the HGA 110 to access portions ofthe disk 120 being mounted on a pivot-shaft 148 with an interposedpivot-bearing assembly 152.

With further reference to FIG. 1, in accordance with an embodiment ofthe invention, electrical signals, for example, current to the voicecoil 140 of the VCM, write signal to and read signal from the PMR head110 a, are provided by a flexible cable 156. Interconnection between theflexible cable 156 and the head 110 a may be provided by anarm-electronics (AE) module 160, which may have an on-boardpre-amplifier for the read signal, as well as other read-channel andwrite-channel electronic components. The flexible cable 156 is coupledto an electrical-connector block 164, which provides electricalcommunication through electrical feedthroughs (not shown) provided by anHDD housing 168. The HDD housing 168, also referred to as a casting,depending upon whether the HDD housing is cast, in conjunction with anHDD cover (not shown) provides a sealed, protective enclosure for theinformation storage components of the HDD 100.

With further reference to FIG. 1, in accordance with an embodiment ofthe invention, other electronic components (not shown), including a diskcontroller and servo electronics including a digital-signal processor(DSP), provide electrical signals to the drive motor, the voice coil 140of the VCM and the head 110 a of the HGA 110. The electrical signalprovided to the drive motor enables the drive motor to spin providing atorque to the spindle 124 which is in turn transmitted to the disk 120that is affixed to the spindle 124 by the disk clamp 128; as a result,the disk 120 spins in a direction 172. The spinning disk 120 creates acushion of air that acts as an air-bearing on which the air-bearingsurface (ABS) of the slider 110 b rides so that the slider 110 b fliesabove the surface of the disk 120 without making contact with a thinmagnetic-recording medium of the disk 120 in which information isrecorded. The electrical signal provided to the voice coil 140 of theVCM enables the head 110 a of the HGA 110 to access a track 176 on whichinformation is recorded. Thus, the armature 136 of the VCM swingsthrough an arc 180 which enables the HGA 110 attached to the armature136 by the arm 132 to access various tracks on the disk 120. Head 110 amay rest upon load/unload platform 190 when head 110 a is not in use.

Information is stored on the disk 120 in a plurality of concentrictracks (not shown) arranged in sectors on the disk 120, for example,sector 184. Correspondingly, each track is composed of a plurality ofsectored track portions, for example, sectored track portion 188. Eachsectored track portion 188 is composed of recorded data and a headercontaining a servo-burst-signal pattern, for example, anABCD-servo-burst-signal pattern, information that identifies the track176, and error correction code information. In accessing the track 176,the read element of the head 110 a of the HGA 110 reads theservo-burst-signal pattern which provides a position-error-signal (PES)to the servo electronics, which controls the electrical signal providedto the voice coil 140 of the VCM, enabling the head 110 a to follow thetrack 176. Upon finding the track 176 and identifying a particularsectored track portion 188, the head 110 a either reads data from thetrack 176 or writes data to the track 176 depending on instructionsreceived by the disk controller from an external agent, for example, amicroprocessor of a computer system. Embodiments of the invention alsoencompass HDD 100 that includes the HGA 110, the disk 120 rotatablymounted on the spindle 124, the arm 132 attached to the HGA 110including the slider 110 b including the head 110 a.

With reference now to FIG. 2, in accordance with an embodiment of thepresent invention, a plan view of a head-arm-assembly (HAA) 200including the HGA 210 is shown. FIG. 2 illustrates the functionalarrangement of the HAA with respect to the HGA 210. The HAA includes thearm 232 and HGA 210 including the slider 210 b including the head 210 a.The HAA is attached at the arm 232 to the carriage 234. In the case ofan HDD having multiple disks, or platters as disks are sometimesreferred to in the art, the carriage 234 is called an “E-block,” orcomb, because the carriage is arranged to carry a ganged array of armsthat gives it the appearance of a comb. As shown in FIG. 2, the armature236 of the VCM is attached to the carriage 234 and the voice coil 240 isattached to the armature 236. The AE 260 may be attached to the carriage234 as shown. The carriage 234 is mounted on the pivot-shaft 248 withthe interposed pivot-bearing assembly 252.

In an embodiment, the enclosure of HDD 100 contains an air passage (suchas depicted in FIGS. 6-8) that allows air to flow between the interiorof the enclosure and the exterior of the enclosure. This air passage isused to equalize the pressure between the interior and the exterior ofthe enclosure when HDD 100 is turned on or turned off. The air passageis covered by a breather filter, which is a filter which prevents anyairborne particles from entering the interior of the enclosure of HDD100. FIG. 7 is an illustration of the flow of air through an air passage710 covered by a breather filter according to an embodiment of theinvention.

The air passage and breather filter may be positioned anywhere in theenclosure of HDD 100; however, it may be advantageous to position thebreather filter as close as possible to the center of HDD 100 tominimize the portions of the interior of HDD 100 which are at a lowerpressure than the outside of the enclosure of HDD 100. Other locationsfor the breather filter besides the center of HDD 100 may also besuitable for the detection of a leak, and the location of the breatherfilter need only be at a pressure point that is lower than the probablelocation of a leak.

The air passage may be implemented using a variety of different shapes.For example, the air passage may be relatively straight, as shown byFIG. 7. Alternately, the air passage may be non-linear. To illustrate,consider FIG. 8, which is a cross-sectional view of a cover comprising abreather filter with a diffusion channel according to an embodiment ofthe invention. As shown by FIG. 8, the air passage in the cover of FIG.8 is non-linear, and the flow of air through the air passage follows acurvy path from the opening to the exterior of HDD 100 to the opening ofthe interior of HDD 100.

In an embodiment, HDD 100 may contain a differential pressure sensor (asdepicted by FIG. 6) capable of measuring a difference in pressurebetween the interior of the enclosure of HDD 100 and the exterior of theenclosure of HDD 100. The differential pressure sensor may be locatedanywhere in which this difference in pressure may be measured. Forexample, in an embodiment, the pressure sensor is located within the airpassage covered by breather filter. In an embodiment, the structure ofthe breather filter and the pressure sensor enables the breather filterand the pressure sensor to be located anywhere in a cover or a basecasting of HDD 100.

In another embodiment, HDD 100 may contain an atmospheric pressuresensor. An atmospheric pressure sensor is a sensor which can determinethe altitude at which HDD 100 is presently located. For example, theatmospheric pressure sensor may determine the whether HDD 100 ispresently located at sea level or at a high elevation. The atmosphericpressure sensor may be used to determine the change in altitude of HDD100 and to allow HDD 100 to make adjustments to optimize the head/diskspacing via the TFC heater element to compensate for changes inhead/disk separation or flying height based on the current altitude ofHDD 100. The pressure sensor depicted by FIG. 6 may correspond to anatmospheric pressure sensor in an embodiment. The atmospheric pressuresensor may be located in any location within HDD 100, including theelectrical printed circuit board (PCB) of HDD 100.

In an embodiment, the differential pressure sensor provides differentialpressure data that describes changes, over a period of time, in thedifference in pressure between the interior of the enclosure of HDD 100and the exterior of the enclosure of HDD 100. This differential pressuredata may be stored on the disk of the HDD or in flash memory (electricalcard of the HDD). In such an embodiment, HDD 100 may comprise flashmemory (not depicted) within the interior of the enclosure of HDD 100.The differential pressure data recorded by the pressure sensor may bestored in the flash memory.

Atmospheric pressure data, which describes the current elevation of HDD100, may also be recorded from the atmospheric pressure sensor to trackthe change in altitude of HDD 100. In an embodiment, atmosphericpressure may identify the altitude of HDD 100 at different points intime. In an embodiment, atmospheric pressure data may be recorded in anylocation as differential pressure data.

In an embodiment, based on the atmospheric pressure data, HDD 100 mayperform a change in the TFC settings of all the heads to compensate forthe decrease in head/disk separation typically experienced when goingfrom sea-level to a high altitude. For example, if at sea-level thehead/disk separation is at 10 nanometers, then when HDD 100 is moved toan altitude of 3300 meters a decrease of 2 nanometers in the distancebetween the head and the disk is usually observed. To compensate, theTFC settings may be adjusted to for the 2 nanometer drop in thehead/disk separation. Alternatively, when moving HDD 100 from analtitude of 3300 meters back to sea-level, the TFC settings of the headsmay be adjusted to effect a 2 nanometer increase in the distance thehead is positioned away from the surface of the disk to reflect thatfact that the head flies closer to the surface of the disk at sea-levelthan at an altitude of 3300 meters.

Differential pressure data and/or atmospheric pressure data may also bestored directly within the hard disk drive on “reserved” tracks of theHDD. Typically, these reserved tracks are only accessible by the HDDoperating system and not by the user.

In an embodiment, HDD 100 comprises a risk assessment component (notdepicted) capable of determining an expression of how likely it is thatHDD 100 will experience an imminent error in operation based, at leastin part, upon the difference in pressure measured by the differentialpressure sensor. As shall be explained in additional detail below, therisk assessment component may also consider other factors, such as howmany airborne particles or how much undesirable chemical vapors arewithin the interior of the enclosure of HDD 100, in determining howlikely it is that HDD 100 will experience an imminent error.

The risk assessment component is also configured to communicate, to auser of HDD 100, how likely it is that HDD 100 will experience animminent error in operation based upon the difference in pressuremeasured by the differential pressure sensor. Additional details abouthow the risk is communicated to the user shall be provided in thesection entitled “Communicating the Risk Assessment to a User.”

Having described an illustrative description of a hard-disk drive (HDD)according to an embodiment of the invention, the process of detecting aleak within the enclosure of the HDD shall now be presented in greaterdetail.

Detecting a Leak within the Enclosure of an HDD

FIG. 3A is a flowchart 300 depicting the functional steps involved inpredicting operational problems in an HDD according to an embodiment ofthe invention. Embodiments of the invention predict operational problemsby detecting a leak within the enclosure of the HDD and assessing theseverity of a detected leak. Embodiments assess a more severe leakwithin the enclosure of an HDD to pose a more significant risk of animminent operational problem than a less severe leak. This is so becauseas the severity of the leak increases, the number of harmful airborneparticles that have likely been introduced into the interior of theenclosure of the HDD also increases.

Initially, in step 310, the difference in pressure between the interiorof the enclosure of the HDD and the exterior of the HDD is measured.Step 310 may be performed by the differential pressure sensor. In anembodiment, the differential pressure sensor may be located within thebreather filter.

The differential pressure sensor may store differential pressure datathat describes changes, over a period of time, in the difference inpressure between the interior of the enclosure of HDD 100 and theexterior of the enclosure of HDD 100. Alternately, the differentialpressure sensor may not record any historical data about the differencein pressure between the interior and exterior of the enclosure of HDD100, but instead, may only maintain the current difference in pressurebetween the interior and exterior of the enclosure of HDD 100.

In step 320, the risk assessment component determines an expression(denoted an “expression of risk”) of how likely it is that HDD 100 willexperience an imminent error in operation. The expression of risk maycorrespond to any description, label, string, or identifier thatcharacterizes how likely it is that HDD 100 will soon experience anerror in operation, such as a hard or soft error. For example, theexpression of risk may correspond to an error warning (such as “Caution:Hard Drive Enclosure Breached—Please Service Hard Drive Immediately”) ora percent chance that HDD 100 will soon experience an error. Additionaldetails about the expression of risk are discussed below in the sectionentitled “Characterizing the Risk.”

The risk assessment component may determine the expression of risk instep 320 in response to the occurrence of a particular event orcondition. For example, step 320 may be performed each time HDD ispowered on or when the risk assessment component determines that thedifference in pressure between the interior and exterior of theenclosure of HDD 100 is greater than a particular threshold value.Additional details about when step 320 may be performed are provided inthe section below entitled “When to Determine the Expression of Risk.”

Further, the risk assessment component may consider other factorsbesides the difference in pressure between the interior and exterior ofthe enclosure of HDD 100 in determining the expression of risk (such as,for example, whether the head has recently been loaded or unloaded,whether HDD 100 recently experienced a mechanical shock, the currentaltitude of HDD 100, the current temperature of HDD 100, the currentnumber of airborne particles within HDD 100, and whether chemical vaporhas been introduced within the interior of HDD 100), as elaborated infurther detail below in the section entitled “Additional Factors toConsider When Determining the Expression of Risk.”

In an embodiment, the risk assessment component may determine theexpression of risk based on historical data describing the operatingconditions of the HDD 100 for a certain period of time. For example, therisk assessment component may consider differential pressure datarecorded by the pressure sensor in determining the expression of risk.Differential pressure data is data that describes, for a period of time,the difference in pressure between the interior and exterior of theenclosure of HDD 100. In this way, the risk assessment component mayconsider, not just the current pressure difference, but the pressuredifference between the interior and exterior of the enclosure of HDD 100that existed over an extended period of time. As another example, inaddition to the pressure data, the risk assessment component mayconsider particle data that describes how many airborne particles haveentered the interior of the enclosure of the HDD 100 since the time ofmanufacture of HDD 100. Thus, the risk assessment component may considercharacteristics of HDD 100 over an extended period of time indetermining the expression of risk.

Alternately, in an embodiment, the risk assessment component maydetermine the expression of risk based solely on the current operatingconditions of the HDD 100.

After the expression of risk has been determined, in step 330, the riskassessment component communicates, to a user of HDD 100, the expressionof risk, i.e., how likely it is that HDD 100 will experience an imminenterror in operation. In an embodiment, step 330 may be performedimmediately after each performance of step 320. In another embodiment,step 330 may be performed only in response to certain conditions orevents, such as HDD 100 being powered on, HDD 100 experiencing a bump orshock, moving HDD 100 to a particular altitude, or after the expirationof configurable amount of time.

The risk assessment component may be configured to communicate, to theuser of HDD 100, the expression of risk in response to determining thatthe difference in pressure between the exterior and interior of theenclosure of HDD 100 is greater than a threshold value. In this way, ifthe difference in pressure is of such a magnitude as to indicate a verysizable leak, then user may be immediately notified that HDD 100 has alarge leak within the enclosure of HDD 100 so that the user may takeimmediate action.

The expression of risk may be communicated to the user in a variety ofdifferent ways. For example, the risk assessment component may useS.M.A.R.T. technology (Self-Monitoring, Analysis and ReportingTechnology) to display a message, containing the expression of risk, tothe user on a display coupled to a machine comprising HDD 100 each timeHDD 100 is powered on. Additional details about communicating theexpression of risk to the user are provided in the section belowentitled “Communicating the Risk Assessment to a User.”

In an embodiment, the information obtained in step 330 may be used inthe manufacturing process. During the manufacturing process, HDD 100 maybe subjected to various performance tests to ensure operability of HDD100. For example, HDD 100 may undergo a series of tests to determinewhether HDD 100 will encounter a hard disk crash or other suchoperability problem. If HDD 100 does not pass such a test, then theinformation obtained in step 330 may be useful in diagnosing theproblem. If it can be determined using the information obtained in step330 that an operability problem was caused due to a leak in theenclosure of HDD 100, then the source of the leak can easily beaddressed (for example, a screw or seal may be repaired or replaced)without requiring other portions of HDD 100 (such as the heads ormagnetic-recording disk) to be replaced.

Additional Factors to Consider when Determining the Expression of Risk

FIG. 3B is a flowchart 350 depicting additional factors that certainembodiments of the invention consider when determining the expression ofrisk in performing step 320 of FIG. 3A. Note that while the factorsdepicted in flowchart 350 are depicted as being considered in aparticular order, other embodiments of the invention may consider thefactors depicted in FIG. 3B in a different order, including consideringtwo or more factors in parallel. Further, each factor depicted in FIG.3B is optional and need not be considered, as embodiments of theinvention may be configured not to consider one or more factors depictedin FIG. 3B.

In factor 322, the risk assessment component considers whether aread/write head of HDD 100 has been, or will be, unloaded off of orloaded onto the ramp in determining the expression of risk in step 320.A read/write head of HDD 100 may periodically be loaded on the ramp andoff the disk as a safety measure and to conserve power. When theread/write head loaded on the ramp and off the disk, the disks are stillpowered on and remain spinning. It may be advantageous, in performingstep 320, to consider whether the head has been, or will soon be, loadedor unload off the ramp because HDD 100 may be more susceptible toencountering an error when the head is moved on and off the ramp.

In factor 323, the risk assessment component considers whether HDD 100has recently encountered a mechanical shock in determining theexpression of risk in step 320. When HDD 100 experiences a mechanicalshock, the screws of HDD 100 may become compromised. Thus, the greaterthe magnitude of the mechanical shock, the greater the risk that aninadvertent leak may have been introduced into HDD 100. Thus, inperforming step 320, certain embodiments consider whether HDD 100 hasreceived a mechanical shock, and the magnitude of any such mechanicalshock, in determining the expression of risk in step 320.

In factor 324, the risk assessment component considers the currentaltitude of HDD 100 in determining the expression of risk in step 320.The heads of HDD 100 fly closer to the disk as the altitude at which HDD100 is located increases; consequently, when HDD 100 is at a highaltitude, the tolerance for leaks or too many airborne particles withinthe enclosure of HDD 100 is less than when HDD 100 is at sea level. Thedecrease in tolerance for leaks or airborne particles is due to theheads flying closer to the disk (i.e., a reduction of head/diskclearance) as well as the heads being more susceptible to any airborneparticles that penetrate the drive. Thus, in performing step 320,certain embodiments consider the current altitude of HDD 100 indetermining the expression of risk in step 320, as the higher thealtitude of HDD 100, the lower the tolerance is for leaks and airborneparticles (due to reduction in head/disk clearance) within the enclosureof HDD 100 before an error in operation is encountered.

In factor 325, the risk assessment component considers the currenttemperature of HDD 100 in determining the expression of risk in step320. Temperature affects the distance between the heads and the surfaceof the magnetic-recording disk as the heads of HDD 100 fly as themagnetic-recording disk. In addition, an increase in the temperature ofHDD 100 may cause any leaks or holes within the enclosure of HDD 100 toexpand. If the leakage increases due to temperature, then thesusceptibility of HDD 100 to airborne particles entering the interior ofHDD 100 also increases. Thus, in performing step 320, certainembodiments consider the current temperature of HDD 100 in determiningthe expression of risk in step 320, as the current temperature of HDD100 affects the tolerance for leaks and airborne particles within theenclosure of HDD 100 before an error in operation is encountered.

In factor 326, the risk assessment component considers the number ofairborne particles in determining the expression of risk in step 320.Additional details about the risk assessment component considering thenumber of airborne particles within the interior of the enclosure indetermining the expression of risk in step 320 is provided below in thesection entitled “Counting Airborne Particles within the Interior of theHDD Enclosure.”

In factor 327, the risk assessment component considers the amount ofchemical vapor intrusion in determining the expression of risk in step320. Additional details about the risk assessment component consideringthe amount of chemical vapor intrusion within the interior of theenclosure in determining the expression of risk in step 320 is providedbelow in the section entitled “Detecting Chemical Vapors within theInterior of the HDD.”

Counting Airborne Particles within the Interior of the HDD Enclosure

In an embodiment, HDD 100 includes a particle counter capable ofdetermining the number of airborne particles within the interior of theenclosure of HDD 100. In such an embodiment, the risk assessmentcomponent may additionally consider the number of airborne particleswithin the interior of the enclosure in determining the expression ofrisk. The particle counter may be located in any location within theinterior of HDD 100 which enables the particle counter to assess theairborne particles within the interior of HDD 100, e.g., the particlecounter may be located anywhere on the cover of the base casting of HDD100.

The particle counter may also be capable of determining the shape andsize of the airborne particles within the interior of the enclosure ofHDD 100. The particle counter may record data (denoted “particle data”)describing the number, shape, and/or size of the airborne particleswithin the interior of the enclosure of HDD 100 over a period of time.Particle data describing the size, shape, or nature of airborneparticles within the interior of the enclosure of HDD 100 may be useful,to the manufacturer of HDD 100, in diagnosing a problem with HDD 100.

In an embodiment, the particle counter may continuously record particledata about the number, shape, and/or size of airborne particles andchemical vapors within the interior of the enclosure of HDD 100.Alternately, in an embodiment, the particle counter may determine thenumber, shape, and/or size of airborne particles within the interior ofthe enclosure of HDD 100 in response to the pressure sensor determiningthat the difference in pressure between the interior of the enclosureand the exterior of the enclosure pressure is greater than a certainthreshold.

In an embodiment, the number of airborne particles within the enclosureof HDD 100 may be used by the risk assessment component in determiningthe expression of risk in step 320. Hard-disk drives can typicallyoperate without encountering any problems with a small amount ofairborne particles. However, if the particle counter determines that thenumber of airborne particles within the interior of the enclosure of HDD100 has increased from 100 to 200, then the risk assessment componentmay determine in step 320 the expression of risk should equate to acautionary warning. On the other hand, if the particle counterdetermines that the number of airborne particles within the interior ofthe enclosure of HDD 100 has increased from 100 to 20,000, then the riskassessment component may determine in step 320 the expression of riskshould identify that an operational failure of HDD 100 is imminent. Themanufacture of HDD 100 may configure the behavior of the risk assessmentcomponent with respect to how many airborne particles are required to bepresent within the interior of the enclosure of HDD 100 before the riskassessment component performs a certain action, such as determining aparticular expression of risk.

In an embodiment, the risk assessment component, in performing step 230,may consider one or more of differential pressure data, atmosphericpressure data, and particle data in determining the expression of risk.In an approach, if either the differential pressure data indicates thedifference in pressure exceeds a particular threshold associated with anerror condition or the particle data indicates the number of particlesin the interior of the enclosure exceeds a particle threshold associatedwith an error condition, then the risk assessment component may select aparticular expression of risk that indicates that there is a problemwith HDD 100 and an error may be imminent. In an another approach, ifthe atmospheric pressure data indicates that a change in altitudegreater than a particular threshold has occurred, then HDD 100 may takeappropriate action to compensate the TFC (Thermal Flying Height Control)settings of each head in HDD 100 to reflect a positive or negativechange in head/disk separation due to the change in altitude.

Detecting Chemical Vapors within the Interior of the HDD

In an embodiment, HDD 100 may comprise a chemical vapor sensor. Achemical vapor sensor is a component that is capable of determining thevapor concentration within the interior of the enclosure of a hard-diskdrive, such as HDD 100. The chemical vapor sensor may be located in anylocation within the interior of HDD 100 which enables the chemical vaporsensor to assess the vapor concentration within the interior of HDD 100,e.g., the chemical vapor sensor may be located anywhere on the cover ofthe base casting of HDD 100.

Harmful chemical vapors entering into the interior of HDD 100 areevidence that the enclosure of HDD 100 has a leak. Non-limiting,illustrative examples of harmful chemical vapors include hydrocarbonbased vapor, such as methane vapor, gasoline vapor as well as siloxane(poly-dimethylsiloxane) vapor.

In such an embodiment, the risk assessment component may be configuredto determine the expression of how likely it is that the hard-disk drive(such as HDD 100) will experience an imminent error in operation basedupon the chemical vapor concentration determined by the chemical vaporsensor. For example, the risk assessment component may determine that itis likely that HDD 100 will experience an imminent error in operation ifthe chemical vapor concentration in the interior of HDD 100 exceeds aparticular threshold. In performing step 320, the risk assessmentcomponent may determine the expression of risk based upon data or inputreceived from one or more of the differential pressure sensor, theatmospheric pressure sensor, the particle counter, and the chemicalvapor sensor.

Pressure Sensor Battery

In an embodiment, the differential pressure sensor, the atmosphericpressure sensor, the particle counter, and/or the chemical vapor sensormay be coupled to a battery so that the differential pressure sensor,the atmospheric pressure sensor, the particle counter, and/or thechemical vapor sensor may continue to operate for a period of time afterHDD 100 is powered down. A rechargeable battery using the “flexiblefilm” technology with Lithium-Ion type batteries may be used. In thisway, the differential pressure sensor, the atmospheric pressure sensor,the particle counter, and/or the chemical vapor sensor may continue tomonitor characteristics of the enclosure of HDD 100 during the timewhen, after HDD 100 is powered down, the air within the enclosure stopscirculating and the temperature within the enclosure decreases to roomtemperature.

The battery coupled to a differential pressure sensor, the atmosphericpressure sensor, the particle counter, and/or the chemical vapor sensormay be placed anywhere in the interior of HDD 100. It would beadvantageous to use a battery that is as inexpensive as possible, as thecost of the battery will add to the production cost of HDD 100. In anembodiment, the battery may be a relatively small battery, similar to ahearing aid battery.

In an embodiment, the battery coupled to the differential pressuresensor, the atmospheric pressure sensor, a particle counter, and/or achemical vapor sensor may be selected such that it could be used formany years. When the power remaining in the battery is low (or out), theuser may receive a notification that the battery is low or needsreplaced. This notification may be performed using S.M.A.R.T.technology, which is explained in further detail below.

In an embodiment, the differential pressure sensor, the atmosphericpressure sensor, the particle counter, and/or the chemical vapor sensoris coupled to a rechargeable battery. When HDD 100 is powered on, thepower to HDD 100 may be used to charge the rechargeable battery.

In another embodiment, the differential pressure sensor, the atmosphericpressure sensor, the particle counter, and/or the chemical vapor sensoris coupled to a replaceable battery. In such an embodiment, HDD 100 maycontain a receptacle to removably attach the replaceable battery to HDD100 without exposing the interior of the enclosure of HDD 100 to theexterior of the enclosure of HDD 100.

Characterizing the Risk

The expression of risk may be implemented in a number of different ways.In an embodiment, the expression of risk may correspond to a particularrisk level of a bounded sequence of risk levels. The bounded sequence ofrisk levels may be arranged in order of how likely it is that HDD 100will experience an imminent error in operation. For example, the lowestrisk level in the bounded sequence may correspond to little or no risk,the next risk level in the bounded sequence may correspond to a smallamount of risk, the next risk level in the bounded sequence maycorrespond to a great amount of risk, and the last risk level in thebounded sequence may correspond to an extreme amount of risk.

In another embodiment, the expression of risk may correspond to apercentage that indicates the probability that the hard-disk drive (HDD)will encounter an error in operation in the near future. For example,the expression of risk may be expressed as 0.5% (indicating a smallamount of risk) or 80% (indicating a large amount of risk).

Embodiments of the invention may implement the expression of risk usingan error code or other identifier. For example, if the difference inpressure between the exterior and interior of the enclosure of HDD 100exceeds a certain threshold, then an error condition may result, and theexpression of risk may correspond to the name of the error condition.

Certain embodiments of the invention may implement the expression ofrisk such that the expression of risk includes certain data describe therisk conditions. For example, the expression of risk may identify thedifference in the pressure between the exterior and interior of theenclosure of HDD 100 or identify the number of airborne particles thathave entered the interior of the enclosure of HDD 100 since the time ofmanufacture of HDD 100.

When to Determine the Expression of Risk

In performing step 320, the risk assessment component determines anexpression of risk that characterizes the likelihood that HDD 100 mayexperience on imminent error in operation. Embodiments of the inventionmay perform step 320 in response to various events. In an embodiment,the risk assessment component performs step 320 in response to HDD 100being powered on. In other embodiments, the risk assessment componentmay perform step 320 in response to HDD 100 being idle or otherwise notreading or writing data.

In other embodiments, the risk assessment component may perform step 320in response to the read/write head being loaded on the ramp and off thedisk. A read/write head may periodically be loaded on the ramp and offthe disk as a safety measure and to conserve power. When the read/writehead loaded on the ramp and off the disk, the disks are still powered onand remain spinning. In other embodiments, the risk assessment componentmay perform step 320 in response to the read/write head being loadedonto the disk.

In other embodiments, the risk assessment component may perform step 320in response to HDD 100 receiving a mechanical shock greater than acertain magnitude. It may be advantageous to perform step 320 after HDD100 receives a mechanical shock because the screws can becomecompromised. Thus, in an embodiment, HDD 100 comprises a shock detector,which is a component that is capable of detecting that HDD experienced amechanical shock. In this embodiment, the risk assessment component isconfigured to perform step 320 in response to the shock detectordetermining that HDD 100 has experienced a mechanical shock greater thana particular threshold or magnitude.

In other embodiments, the risk assessment component may perform step 320in response to HDD 100 being at or above a particular altitude. Theatmospheric pressure sensor can determine the change in altitude. It maybe advantageous to perform step 320 if HDD 100 is at or above aparticular altitude because the heads fly closer to the disk when HDD100 is at high altitude; consequently, when HDD 100 is at a highaltitude, the tolerance for leaks or too many airborne particles withinthe enclosure of HDD 100 is less than when HDD 100 is at sea level. Forexample, when HDD 100 is at sea level, there may be about 6 nanometersof clearance between a read/write head and the disk; on the other hand,when HDD 100 is at a high altitude, the read/write head may fly over thedisk with only about 4 nanometers of clearance. Thus, in an embodiment,HDD 100 also comprises an absolute pressure sensor, which is a componentthat is capable of identifying the current altitude of HDD 100. In thisembodiment, the risk assessment component is configured to perform step320 in response to the atmospheric pressure sensor determining that HDD100 is at or above a particular altitude.

In other embodiments, the risk assessment component may perform step 320in response to HDD 100 being at or above a particular temperature, asenvironmental temperature changes within HDD 100 may affect the distancebetween the read/write head of HDD 100 and the surface of themagnetic-recording disk. In an embodiment, HDD 100 comprises atemperature sensor, which is a component that is capable of determiningthe temperature within the interior of the enclosure of HDD 100. In suchan embodiment, the risk assessment component is configured to performstep 320 in response to the temperature sensor determining that thetemperature within the interior of the enclosure of the hard-disk drive(HDD) is greater than a particular threshold or temperature.

In other embodiments, the risk assessment comprises a chemical sensor.In such an embodiment, the risk assessment component is configured toperform step 320 e in response to a chemical vapor intrusion inside thedrive. This determination is obtained via the chemical vapor sensor thatdetects a hydrocarbon vapor or siloxane (poly-dimethylsiloxane) vaporabove a threshold amount.

Communicating the Risk Assessment to a User

In step 330, the risk assessment component communicates the expressionof risk to the user of HDD 100. In an embodiment, the expression of riskmay be communicated to the user using S.M.A.R.T. technology. S.M.A.R.T.(Self-Monitoring, Analysis and Reporting Technology) technology isimplemented into virtually all modern hard disks. A special programinside the hard-disk drive employing S.M.A.R.T. technology constantlymonitors the condition of a variety of attributes of the hard-diskdrive, such as the driver, the disk heads, the surface state, and theelectronics. The S.M.A.R.T. technology monitors the hard-disk drive foranything that might seem out of the ordinary, documents it, and analyzesthe data. If the S.M.A.R.T. technology detects a condition thatindicates a problem, the S.M.A.R.T. technology is capable of notifyingthe user (or system administrator).

In an embodiment, step 330 may be performed by using S.M.A.R.T.technology to notify the user of HDD 100 of the expression of risk.Typically, S.M.A.R.T. technology communicates information to the user bydisplaying a message on a display coupled to a machine comprising thehard-disk drive each time the hard-disk drive is powered on.Alternately, in an embodiment, a software program executing on acomputer could communicate with the S.M.A.R.T. technology and/or therisk assessment component to retrieve the assessment of risk for displayto the user.

Atmospheric Pressure Sensor

FIG. 9 is a flowchart depicting the functional steps of correcting thedistance between the heads of an HDD and the disk in response to achange in altitude of the HDD according to an embodiment of theinvention. By performing the steps of FIG. 9, HDD 100 may adjust theThermal Fly Height Control (TFC) settings of the heads to reflect achange in altitude. Normally, the TFC settings allow a head to dropabout 4 nanometers closer to the surface of the magnetic-recording diskto allow the read/write heads to fly over the surface of themagnetic-recording disk in close proximity to the surface of themagnetic-recording disk.

In step 910, the current altitude of HDD 100 is determined by theatmospheric pressure sensor. The atmospheric pressure sensor may recordatmospheric pressure data that identifies the altitude of which HDD 100was located at different points in time. Alternatively, the atmosphericpressure data may only identify the current altitude of HDD 100 withoutdescribing a historical record of the altitude of HDD 100.

In step 920, a determination is made as to whether the TFC settings ofthe heads of HDD 100 should be updated to reflect the current altitudeof HDD 100. The heads of HDD 100 typically fly over the surface of themagnetic-recording disk with 10 nanometers clearance when HDD 100 is atsea level. However, when HDD 100 is located at an altitude of 3300meters, the heads typically fly over the surface of themagnetic-recording disk with only 8 nanometers clearance, which is 2nanometers less than when HDD 100 is located at sea level.

Thus, in an embodiment, when HDD 100 determines that HDD 100 is locatedat an altitude greater than a particular level, then an electroniccomponent of HDD 100 adjusts the TFC settings of the heads of HDD 100,as the heads will fly closer to the surface of the magnetic-recordingdisk at elevation. In the example above, in the performance of step 920,the TFC settings for the heads of HDD 100 will be adjusted to undergo a−2 nanometer change, if HDD 100 has been brought from sea level to analtitude of 3300 meters, as the heads of HDD 100 fly 2 nanometers closerto the surface of the disk at 3300 meters compared to sea level. As theheads fly closer to the surface of the magnetic-recording disk ataltitude (in this example 3300 meters), it is not necessary for the TFCsettings to drop the head closer to the surface of themagnetic-recording disk by 4 nanometers, as dropping the head by only 2nanometers positions the head over the surface of the magnetic-recordingdisk the same distance away from the surface of the magnetic-recordingdisk as when HDD 100 is at sea level.

In an embodiment (denoted the “single sensor embodiment”), theatmospheric pressure sensor may be implemented using the same pressuresensor as the differential pressure sensor. Thus, embodiments of theinvention may employ a single pressure sensor to perform the functionsdescribed herein attributed to both the differential pressure sensor andthe atmospheric pressure sensor. In such an embodiment, an electroniccontrol of HDD 100 may instruct the pressure sensor to operate as eithera differential pressure sensor as described herein or an atmosphericpressure sensor as described herein.

According to one approach for implementing the single sensor embodiment,when HDD 100 is initially powered on, an electronic control of HDD 100instructs the single pressure sensor to function as a differentialpressure sensor to determine whether there is a leak within theenclosure of HDD 100. Thereafter, the electronic control of HDD 100instructs the single pressure sensor to function as an atmosphericpressure sensor to determine if present elevation of HDD 100 has changedsince HDD 100 was last powered on. If HDD 100 detects a leak within theenclosure of HDD 100, then HDD 100 warns the user of the leak via theS.M.A.R.T. interface. Contemporaneously, if HDD 100 determines that thechange in elevation of HDD 100 since the last time HDD 100 was poweredon is greater than a particular threshold, then HDD 100 adjusts the TFCsettings of the heads so that they fly with the proper clearance overthe surface of the magnetic-recording disk despite the current altitudeof HDD 100. The user of HDD 100 may be informed of any change to the TFCsettings via the S.M.A.R.T. interface.

In the foregoing specification, embodiments of the invention have beendescribed with reference to numerous specific details that may vary fromimplementation to implementation. Thus, the sole and exclusive indicatorof what is the invention, and is intended by the applicants to be theinvention, is the set of claims that issue from this application, in thespecific form in which such claims issue, including any subsequentcorrection. Any definitions expressly set forth herein for termscontained in such claims shall govern the meaning of such terms as usedin the claims. Hence, no limitation, element, property, feature,advantage or attribute that is not expressly recited in a claim shouldlimit the scope of such claim in any way. The specification and drawingsare, accordingly, to be regarded in an illustrative rather than arestrictive sense.

What is claimed is:
 1. A hard-disk drive (HDD), comprising: anenclosure, wherein the enclosure contains an air passage that allows airto flow between the interior of the enclosure and the exterior of theenclosure, wherein the air passage is covered by a breather filter; adifferential pressure sensor capable of measuring a difference inpressure between the interior of the enclosure and the exterior of theenclosure; a risk assessment component capable of determining anexpression of how likely it is that the hard-disk drive (HDD) willexperience an imminent error in operation based, at least in part, uponthe difference in pressure measured by the differential pressure sensor,wherein the risk assessment component is configured to communicate, to auser of the hard-disk drive (HDD), the expression of how likely it isthat the hard-disk drive (HDD) will experience an imminent error inoperation based, at least in part, upon the difference in pressuremeasured by the differential pressure sensor; a magnetic-recording head;a magnetic-recording disk rotatably mounted on a spindle; a drive motormounted in said enclosure, said drive motor having a motor shaftattached to said spindle for rotating said magnetic-recording disk; anda voice-coil motor configured to move said magnetic-recording head toaccess portions of said magnetic-recording disk.
 2. The hard-disk drive(HDD) of claim 1, wherein the differential pressure sensor is located inthe air passage covered by the breather filter.
 3. The hard-disk drive(HDD) of claim 1, wherein the differential pressure sensor storesdifferential pressure data that describes changes, over a period oftime, in the difference in pressure between the interior of theenclosure and the exterior of the enclosure, and wherein the riskassessment component determines the expression of how likely it is thatthe hard-disk drive (HDD) will experience an imminent error in operationusing the differential pressure data.
 4. The hard-disk drive (HDD) ofclaim 3, further comprising: flash memory within the interior of theenclosure of the hard-disk drive (HDD), and wherein the differentialpressure data is stored in the flash memory.
 5. The hard-disk drive(HDD) of claim 1, wherein the differential pressure sensor is capable ofoperating as an atmospheric pressure sensor that identifies the currentaltitude of the hard-disk drive (HDD), and wherein the risk assessmentcomponent is configured to determine the expression based upon thecurrent altitude of the hard-disk drive (HDD).
 6. The hard-disk drive(HDD) of claim 1, further comprising: a shock detector, wherein theshock detector is a component that is capable of detecting that thehard-disk drive (HDD) experienced a mechanical shock, and wherein therisk assessment component is configured to determine the expression ofhow likely it is that the hard-disk drive (HDD) will experience animminent error in operation upon the shock detector determining that thehard-disk drive (HDD) has experienced a mechanical shock greater than aparticular threshold.
 7. The hard-disk drive (HDD) of claim 1, furthercomprising: a temperature sensor, wherein the temperature sensor is acomponent that is capable of determining the temperature within theinterior of the enclosure of the hard-disk drive (HDD), and wherein therisk assessment component is configured to determine the expression ofhow likely it is that the hard-disk drive (HDD) will experience animminent error in operation upon the temperature sensor determining thatthe temperature within the interior of the enclosure of the hard-diskdrive (HDD) is greater than a particular threshold.
 8. The hard-diskdrive of claim 1, further comprising: a chemical vapor sensor, whereinthe chemical vapor sensor is a component that is capable of determiningthe chemical vapor concentration within the interior of the enclosure ofthe hard-disk drive (HDD), and wherein the risk assessment component isconfigured to determine the expression of how likely it is that thehard-disk drive (HDD) will experience an imminent error in operationbased upon the chemical vapor concentration within the interior of thehard-disk drive (HDD).
 9. The hard-disk drive (HDD) of claim 1, whereinthe differential pressure sensor is coupled to a rechargeable battery,and wherein the differential pressure sensor uses power supplied by therechargeable battery to measure the difference in the pressure betweenthe interior of the enclosure and the exterior of the enclosure for alength of time after the hard-disk drive (HDD) is no longer beingsupplied power.
 10. The hard-disk drive (HDD) of claim 1, wherein thedifferential pressure sensor is coupled to a replaceable battery, andwherein the hard-disk drive (HDD) contains a receptacle to removablyattach the replaceable battery to the hard-disk drive (HDD) withoutexposing the interior of the enclosure to the exterior of the enclosure.11. The hard-disk drive (HDD) of claim 1, wherein the risk assessmentcomponent is configured to communicate, to the user, the expression inresponse to the hard-disk drive (HDD) being powered on.
 12. Thehard-disk drive (HDD) of claim 1, further comprising: a particle countercapable of determining the number of airborne particles within theinterior of the enclosure of the hard-disk drive (HDD), wherein the riskassessment component additionally considers the number of airborneparticles within the interior of the enclosure in determining theexpression of how likely it is that the hard-disk drive (HDD) willexperience an imminent error in operation.
 13. The hard-disk drive (HDD)of claim 12, wherein the particle counter is capable of determining ashape and size of the airborne particles within the interior of theenclosure of the hard-disk drive (HDD), and wherein the particle counterrecords data describing the number, shape, and size of the airborneparticles over a period of time.
 14. The hard-disk drive (HDD) of claim12, wherein the particle counter determines the number of airborneparticles within the interior of the enclosure of the hard-disk drive(HDD) upon the differential pressure sensor determining that thedifference in pressure between the interior of the enclosure and theexterior of the enclosure pressure is greater than a certain threshold.15. The hard-disk drive (HDD) of claim 1, wherein the expression maycorrespond to a particular risk level of a bounded sequence of risklevels, and wherein a first risk level that is higher in the boundedsequence of risk levels is associated with more risk of an error inoperation than a second risk level that is lower in the bounded sequenceof risk levels.
 16. The hard-disk drive (HDD) of claim 1, wherein theexpression corresponds to a percentage that indicates the probabilitythat the hard-disk drive (HDD) will encounter an error in operation inthe near future.
 17. The hard-disk drive (HDD) of claim 1, wherein therisk assessment component is configured to communicate, to the user ofthe hard-disk drive (HDD), that the hard-disk drive (HDD) is likely toexperience imminent failure upon determining that the difference inpressure is greater than a threshold value.
 18. The hard-disk drive(HDD) of claim 1, wherein the differential pressure sensor has astructure that allows the differential pressure sensor to be locatedanywhere in a cover or a base casting of the hard-disk drive (HDD). 19.A hard-disk drive (HDD), comprising: an enclosure, wherein the enclosurecontains an air passage that allows air to flow between the interior ofthe enclosure and the exterior of the enclosure, wherein the air passageis covered by a breather filter; a differential pressure sensor capableof measuring a difference in pressure between the interior of theenclosure and the exterior of the enclosure; particle counter capable ofdetermining the number of airborne particles within the interior of theenclosure of the hard-disk drive (HDD); an error detection componentcapable of determining an expression of how likely it is that thehard-disk drive (HDD) will experience an imminent error in operationbased, at least in part, upon the difference in pressure and the numberof airborne particles within the interior of the enclosure; amagnetic-recording head; a magnetic-recording disk rotatably mounted ona spindle; a drive motor mounted in said enclosure, said drive motorhaving a motor shaft attached to said spindle for rotating saidmagnetic-recording disk; and a voice-coil motor configured to move saidmagnetic-recording head to access portions of said magnetic-recordingdisk.
 20. The hard-disk drive (HDD) of claim 19, wherein the riskassessment component is configured to determine that the expressionindicates that the hard-disk drive (HDD) will likely experience animminent error in operation if (a) the difference in pressure is greaterthan a first threshold and (b) the number of airborne particles withinthe interior of the enclosure is greater than a second threshold. 21.The hard-disk drive (HDD) of claim 19, wherein the risk assessmentcomponent is configured to determine that the expression indicates thatthe hard-disk drive (HDD) will likely experience an imminent error inoperation if (a) the difference in pressure is greater than a firstthreshold or (b) the number of airborne particles within the interior ofthe enclosure is greater than a second threshold.
 22. Amachine-implemented method for determining the likelihood that ahard-disk drive (HDD) will experience an imminent error in operation,comprising: measuring a difference in pressure between an interior of anenclosure of the hard-disk drive (HDD) and an exterior of the enclosureof the hard-disk drive (HDD); upon determining that the difference inpressure between the interior and the exterior of the enclosure of thehard-disk drive (HDD) is greater than a particular threshold, a riskassessment component determining that the hard-disk drive (HDD) islikely to experience an imminent error in operation; and communicating,to a user of the hard-disk drive, that the hard-disk drive (HDD) islikely to experience an imminent error in operation.